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Originally Posted by JimmyP
That company showed up and did some measurements and came up with 38000 BTU's/ hr heat loss. So a 3 or 3.5 ton system needed.

My electrical utility bill average for Dec to Feb was 1500kw /month this is 170500 btu's day and 12 hours / day ( darkness without solar gain) of usage would be 14208 btu's/hr. There is no way I would need 38000btu's hr.
Maybe he likes to size for -6 'F with an assumed HIGH infiltration rate.
.........................................

One needs to review electric usage by the hour if you wish to establish heat capacity required
based on power usage
and equipment heat output
or one must compensate for Heating Degree Days (HDD) versus Design Temperature.

PEAK LOAD might be 1.5 to 2.5 X the Average usage depending of the day, week or month.
For example, Design Temperature = 10'F and Average Temperature = 30'F ( HDD = 65 - 30 = 35)

dT Design = 70 -10 = 60
dT HDD = 70 - 35 = 35
60 / 35 = 1.7

dT HDD = 70 - 45 = 25 for a warmer month, week or day
60/ 25 = 2.4

If your average temperature for Dec - Febr was 30'F ( HDD = 35 * 90 days = 3150),
one would use 1.7 * portion of electric bill used for heating IF electric strip was used.

X C.O.P. if heat pump is used.

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Dan

For here the average daily low for that period 16F and the daily average is 23F. That would make dt HDD 65-16= 49. 49 x 90Days = 4410 HDD
A design of 10 would be Design dT of 60. So 60/49 =1.2 that would be 1500 x 1.2 average or 60 kw /day.

Last night I used 16 kw in 9 hours 10 pm to 7 am with an outside temp of 28 and an inside temperature of 63.

Jimmy
Last edited by JimmyP; 04-10-2013 at 06:38 AM. Reason: add information.

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Originally Posted by hvacvegas
we don't base a load on average.
you may keep your thermostat at a different temperature than the manual J suggested temp.
What is the design temperature based on? Average or what ?

4. Originally Posted by JimmyP
What is the design temperature based on? Average or what ?
It's based on an expectation of how cold/hot it normally gets. Not average temperatures.
Also, what he designed your indoor temp makes a big difference also.

Both these numbers have standards based on location, that can be deviated.

All this crazy math stuff is why we make the little bucks, and you should listen to the professionals that come out to your home.

I personally think you already have decided what you want in your house.
Your just looking for someone whos going to agree with you.

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Originally Posted by JimmyP
Dan

For here the average daily low for that period 16F and the daily average is 23F. That would make dt HDD 65-16= 49. 49 x 90Days = 4410 HDD
A design of 10 would be Design dT of 60. So 60/49 =1.2 that would be 1500 x 1.2 average or 60 kw /day.

Last night I used 16 kw in 9 hours 10 pm to 7 am with an outside temp of 28 and an inside temperature of 63.

Jimmy
So what's the equipment?
Strip ?
or heat pump?

Mfg :
Model:

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Originally Posted by JimmyP
What is the design temperature based on? Average or what ?
Temperature that is only exceeded for 175 hours [2% of 8,760] / year _ 30 year average.

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Originally Posted by JimmyP
Dan

For here the average daily low for that period 16F and the daily average is 23F. That would make dt HDD 65-16= 49. 49 x 90Days = 4410 HDD
A design of 10 would be Design dT of 60. So 60/49 =1.2 that would be 1500 x 1.2 average or 60 kw /day.

Last night I used 16 kw in 9 hours 10 pm to 7 am with an outside temp of 28 and an inside temperature of 63.

Jimmy
WHY is your inside temp dropping to 63?

Where does 1500 come from?

If you wish to Use average all meaningful data is destroyed.

Don't you have your electric usage for the last 50 months or so?
Each month can be correlated to HDD.

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Originally Posted by dan sw fl
WHY is your inside temp dropping to 63?

Where does 1500 come from?

If you wish to Use average all meaningful data is destroyed.

Don't you have your electric usage for the last 50 months or so?

Each month can be correlated to HDD.
I set it to 63 for night time from 11pm to 6 AM

Actual usge in KW from electrical bills for 1500/month for 3 month period used 4500 in 90 days.

Yes for 24 months. it uses electric baseboard heat.

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Originally Posted by hvacvegas
It's based on an expectation of how cold/hot it normally gets. Not average temperatures.
Also, what he designed your indoor temp makes a big difference also.

Both these numbers have standards based on location, that can be deviated.

All this crazy math stuff is why we make the little bucks, and you should listen to the professionals that come out to your home.

I personally think you already have decided what you want in your house.
Your just looking for someone whos going to agree with you.
I have done a load calculation so I should have an idea what is required. He didn't put in insulation values. He did put in running wall length and window sizes. I have a vaulted ceiling that is triangular on top. He put in total height for that wall of 21 ft and he should have used 15.5 ft He didn't know what manual J was, He said he puts the numbers in the program and it gives a recomendation . It may be a manual J program. I don't know. The guy designing the Duckwork did not know what Manual D was. He had a slide card giving him pressure loss for pipe size and length.

The equipment sizing was based on heating load required, from what I gather is wrong according to the experts.

Jimmy

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Dan

Some numbers from my electrical bills. Electric baseboard heat only. Total usage 6824kwh Usage for electrical only is 4784kwh ( 500 /month for other usage) HDD for that peroid 1834.

http://stjohns.weatherstats.ca/metrics/hdd.html.

Last month used 1295kwh for heat and 552 HDD's.

Jimmy

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Originally Posted by JimmyP
Actual usge in KW from electrical bills ...

Yes for 24 months. it uses electric baseboard heat.
With EACH of the 24 months data being Kept a Secret, NO ONE CAN DO A REAL LOAD CALC based on Actual Usage.

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Originally Posted by JimmyP
Dan

Some numbers from my electrical bills.
Electric baseboard heat only.
Total usage 6824kwh Usage for electrical only is 4784kwh ( 500 /month for other usage) HDD for that peroid 1834.

http://stjohns.weatherstats.ca/metrics/hdd.html.

Last month used 1295kwh for heat and 552 HDD's. Jimmy
Last months data of 1,284 KWH FOR HEAT with 552 HDD equates to 21,000 BTU/HR

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## Sorry no secret

Originally Posted by dan sw fl
With EACH of the 24 months data being Kept a Secret, NO ONE CAN DO A REAL LOAD CALC based on Actual Usage.
Here are the numbers:

The estimated values are from when they can't read the meter if the road or drivway is not yet plowed after a heavy snowfall and this happens a few times during the winter as we are located in a remote area and sometimes the road is not plowed right away.

Date (Y/M/D) Energy Reading Read / Estimate kwh Used Days Usage Per Day HDD
2013-03-21 46657 Read 1795 29 62 562
2013-02-20 44862 Read 2906 30 97 592
2013-01-21 41956 Estimated 2003 33 61 674
2012-12-19 39953 Estimated 1312 26 50 567
2012-11-23 38641 Read 1068 31 34 391
2012-10-23 37573 Read 438 32 14 269
2012-09-21 37135 Estimated 760 30 25 99
2012-08-22 36375 Read 633 29 22 30
2012-07-24 35742 Read 956 34 28 32
2012-06-20 34786 Read 733 27 27 246
2012-05-24 34053 Read 1214 31 39 313
2012-04-23 32839 Read 1314 32 41 381
2012-03-22 31525 Read 1633 29 56 1865 (Jan-March)
2012-02-22 29892 Read 2646 30 88
2012-01-23 27246 Read 2694 34 79
2011-12-20 24552 Read 1774 28 63 1317 (Oct -Dec)
2011-11-22 22778 Estimated 866 28 31
2011-10-25 21912 Read 532 34 16
2011-09-21 21380 Estimated 541 29 19
2011-08-23 20839 Read 598 30 20 321 (July - Sep)
2011-07-24 20241 Read 561 33 17
2011-06-21 19680 Read 829 32 26
2011-05-20 18851 Read 1198 30 40
2011-04-20 17653 Read 3242 29 112 1077 ( April-June)
2011-03-22 14411 Estimated 1336 29 46
2011-02-21 13075 Estimated 1568 32 49
2011-01-20 11507 Read 1519 31 49 1825 (Jan-Mar)

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